Multiband and wideband 90° polarization rotators

Abstract

Inspired by techniques utilized in the design of frequency-selective surfaces (FSSs), multi-band and wideband 90° polarization rotators are proposed in this letter. The basic structure is constructed from three layers. The front and back layers contain metal wire grids orthogonal to each other, while the middle layer consists of resonant elements with 45° twisted angle, which plays the main role in determining the overall response of the structure. Employing single and multiple resonators in the middle layer, first-order single- and multi-band are achieved. By cascading two first-order middle layers, a second-order response is accomplished. A very wideband response is achieved by utilizing a wideband resonant element in the middle layer. Several design examples are presented and simulated, two of them are fabricated and tested to validate the simulated results.